1. Field of the Invention
The present invention relates to a filling nozzle of a liquid filling machine and more particularly to a filling nozzle which is suitable for use in a pressurizing tank type liquid filling apparatus in which a predetermined liquid pressure is constantly applied to the liquid in a liquid flow path.
2. Prior Art
The liquid filling apparatus described in Japanese Patent Application Laid-Open (Kokai) No. 11-193094 is a rotary type filling apparatus. This filling apparatus includes filling nozzles, a pressurizing tank and a liquid passage (pipe channel). The filling nozzles are disposed at fixed intervals in a plurality of locations along the circumferential direction of a rotary body that rotates continuously, and they fill containers with a liquid. The pressurizing tank stores the liquid, and the liquid passage (pipe channel) branches from the pressurizing tank via a distribution chamber and is connected to the respective filling nozzles.
This liquid filling apparatus uses filling nozzles which are opened and closed by opening-and-closing valves that are raised and lowered only in the discharge ports that are provided at the lower ends of the nozzles. In such an apparatus, since a predetermined liquid pressure is constantly applied to the liquid inside the flow path, the gap at the discharge ports is abruptly constricted so that the flow velocity of the liquid increases when the discharge ports of the filling nozzles are closed by the opening-and-closing valves. As a result, the liquid is forcefully scattered to the outsides from the discharge ports. Thus, the filling apparatus has several problems. The liquid with which the containers are filled is caused to foam, and the containers are contaminated by the scattered liquid. Furthermore, after the discharge ports are closed off, liquid droplets adhere to the lower end of the discharge ports, and these droplets fall as a dripping liquid, contaminating the containers and the area around the containers.
In order to solve these problems, the inventors of the present application studied the use of a filling nozzle that includes a throttle valve installed on the upstream side of the opening-and-closing valve of the discharge port. Such a nozzle is disclosed in Japanese Utility Model Application Laid-Open (Kokai) No. 61-123097, Japanese Patent Application Laid-Open (Kokai) No. 4-201801, Japanese Utility Model Application Publication (Kokoku) No. 7-2479, Japanese Patent No. 2919202, etc. The inventors"" study, however, found several problems in the nozzles disclosed in these prior art.
The problems of the filling nozzle disclosed in Japanese Utility Model Application Laid-Open (Kokai) No. 61-123097 are as follows: (1) In cases where a so-called xe2x80x9ccleaning-in-placexe2x80x9d or xe2x80x9cCIPxe2x80x9d in which cleaning water is caused to flow through the nozzle with the discharge port opened, the areas between O-rings are cleaned. As a result, it is necessary to disassemble the nozzle, making the maintenance characteristics poor. (2) Numerous O-rings are installed, and they are in constant rubbing contact with the inside surface of the nozzle main body. Such O-rings become worm, and debris is admixed with the liquid. Thus, O-ring replacement must be performed frequently, and this requires disassembly of the nozzle, resulting in poor maintenance characteristics. (3) Because a throttle valve part is installed in the supply opening in the nozzle""s side wall, the structure of the throttle valve body is complicated, and thus the working costs tend to be high amount.
In the filling nozzle of Japanese Patent Application Laid-Open (Kokai) No. 4-201801, the scattering of the liquid is suppressed to some extent. However, the dripping of this liquid is not suppressed.
In the case of the filling nozzle of Japanese Patent Application Publication (Kokoku) No. 7-2479, the liquid located beneath the larger-diameter intermediate shaft part is pushed toward the discharge port when the larger-diameter intermediate shaft part is lowered. As a result, a jet of the liquid from the gap at the discharge port immediately prior to the closing of the opening-and-closing valve is suppressed.
The filling nozzle of Japanese Patent No. 291202 has the following problems: (1) The structure of the throttle valve is complicated, and costs are high. (2) Since the throttle valve is closed off by the driving force of a spring, there is a lack of stability in the operation of the throttle valve in cases where the filling process involves a high-viscosity liquid. (3) The dripping of the liquid is not suppressed. (4) Cleaning involves disassembly of the nozzle in order to clean away the liquid that has entered the areas of sliding elements, and thus an efficient CIP is not performed. (5) Since the center rod and throttle valve are in a constant sliding motion, matters are generated by wear and admixed in the liquid.
Accordingly, the main object of the present invention is to provide a liquid filling nozzle used in a liquid filling apparatus that with a simple structure suppresses the scattering of liquid from the discharge port in the final stage of filling of the liquid into containers, suppresses the dripping of the liquid after closing the discharge port, has an improved maintenance characteristics and allows cleaning-in-place (CIP) to be performed.
Another object of the present invention is to provide a liquid filling nozzle used in a liquid filling apparatus that prevents the admixture of matters, which are created by wear of the components, into the liquid filled in containers.
The above objects are accomplished by a unique structure for a liquid filling nozzle that includes: a tubular nozzle main body that has a liquid supply opening formed in the side wall and a discharge port formed in the lower end, a center rod disposed inside the nozzle main body concentrically, a raising-and-lowering device which raises and lowers the center rod, and an opening-and-closing valve body which is provided at the lower end of the center rod so as to open the discharge port when the center rod is lowered and to close the discharge port when the center rod is raised; and the liquid that enters via the liquid supply opening flows out from the discharge port through a flow path which is provided between the inside wall surface of the nozzle main body and the outer surface of the center rod; and in the present invention, the liquid filling nozzle further includes a throttle valve mechanism which is disposed below the liquid supply opening inside the nozzle main body and constricts the flow path for the liquid; and
the throttle valve mechanism is comprised of:
a throttle valve seat provided on the inside wall surface of the nozzle main body, and
a throttle valve body provided on the center rod; and
the throttle valve mechanism opens when the center rod is lowered, and, when the center rod is raised, the throttle valve mechanism closes before the opening-and-closing valve body closes off the discharge port, thus constricting the flow path.
In this structure, the opening-and-closing valve body and the throttle valve body can be formed on the center rod integrally, and the throttle valve seat can be formed on the nozzle main body integrally. Instead, the opening-and-closing valve body, throttle valve body and throttle valve seat can be formed as an independent element respectively and mounted on the center rod or on the nozzle main body so as to form an integral body.
In the above throttle valve mechanism: the throttle valve seat is a hollow cylindrical form and disposed on the inside wall surface of the nozzle main body, and the throttle valve body is a solid cylindrical form and disposed on the center rod so as to fit inside the throttle valve seat; and the throttle valve body is separated from the throttle valve seat when the center rod is lowered, and, when the center rod is raised, at least part of the throttle valve body is moved into the throttle valve seat before the opening-and-closing valve body closes off the discharge port, thus constricting the flow path.
In this structure, the throttle valve seat is formed inside the nozzle main body and at the position where the inner diameter defined by the inside wall surface of the nozzle main body is formed smaller, and the throttle valve body is formed on the center rod at a position where the center rod expands outward and its external diameter is formed larger.
It is preferable that the lower part of the throttle valve seat and a larger-diameter portion below such a lower part be formed continuously by a taper, and/or the upper part of the throttle valve body and a smaller-diameter portion above such an upper part be formed continuously by a taper
The above described liquid filling nozzle is especially, well manifested when such a liquid filling nozzle is used in a liquid filling apparatus that is comprised of one or more such liquid filling nozzles, a pressurizing tank that stores a liquid, and a liquid flow path that connects the liquid supply opening of each one of the liquid filling nozzles to the pressurizing tank (see the above-described Japanese Patent Application Laid-Open (Kokai) No. 11-193094). However, the liquid filling nozzle of the present invention can be used also in a liquid filling apparatus of the type in which a metering cylinder is disposed between a liquid tank and liquid filling nozzles so that the liquid is sucked into the metering cylinder from the liquid tank and measured and then the liquid is fed to the liquid filling nozzles by a piston (see the above-described Japanese Patent Application Laid-Open (Kokai) No. 4-201801 and Japanese Utility Model Application Publication (Kokoku) No. 7-2479).